Hot Rods Were quick changes used in drag racing?

They ran these Scheifers in dragsters and funnycars in the early 70's - big 10" ring gear, offset centersection. I used to own one out of a F/C...

 

Scheifer/Eaton, we still have one in a Sand Dragster.

 

Ran this for years on the street. Injected 327 with 4-speed Hydramatic. I believe it lasted as long as it did with less problems with some slippage in the Hydro verses a hammering stick. And 30 pounds of air in the skinny tires.

 

I installed one in an altered years ago, you needed 100 extra HP because the thing weighed so much. It was strong, but unless you changed gears on a regular basis, it made no sense in having one, but you needed 2 incase something broke and you had a backup